1. Field of the Invention
This invention relates to circuit breakers equipped with auxiliary switches to provide an indication of the type of trip, for example, an electronic trip, such as due to an arc fault, as opposed to a thermal trip, and an indication of the open/closed state of the breaker contacts.
2. Background Information
Circuit breakers used in some applications, such as aerospace, by necessity have very small physical dimensions. Traditionally, such very small circuit breakers, which are often referred to as subminiature circuit breakers, have provided only overload protection, typically through use of a bimetal coupled to a spring-loaded operating mechanism. Recently, there has been interest in providing arc fault protection in such circuit breakers. An electronic circuit detects current signatures associated with arcing. An arc fault trip signal generated by the electronic circuit energizes a trip coil that triggers the spring-loaded operating mechanism to open the contacts of the circuit breaker. An example of such a mechanism for providing arc fault protection in a subminiature circuit breaker is disclosed in U.S. Pat. No. 6,225,883.
It is often desirable in circuit breakers providing arc fault protection in addition to overload protection, to provide an indication of the type of fault that has caused the breaker to trip. Commonly owned U.S. patent application Ser. No. 09/845,943, filed on Apr. 30, 2001, provides an illuminated ring around the push/pull handle of the subminiature circuit breaker that pops up to indicate an arc fault trip. An indicator armature, provided in addition to the trip armature on the trip coil, releases a spring that causes the indicator ring to pop-up in response to an arc fault trip.
It is common to equip circuit breakers with auxiliary switches that can be used to provide remote indications of conditions within the circuit breaker. Typically, two types of auxiliary switches are provided, either singly or together. One type, that is commonly referred to as providing a bell alarm, indicates a trip by the circuit breaker. This auxiliary switch is usually actuated off of the trip latch or cradle that only changes position when the circuit breaker is tripped open and not when the circuit breaker is manually opened. The second type of common auxiliary switch is referred to just as the auxiliary switch and provides an indication of the open/closed state of the circuit breaker contacts and is often actuated off of the circuit breaker handle. The subminiature circuit breaker provides a challenge to providing auxiliary switches due to the severe space limitations.